Format: ORAL

Fiorella F. Mazine1, Karinne S. Valdemarin2, Mariana Andreotti1, Eve Lucas3 Vinicius C. Souza2

1 Universidade Federal de São Carlos, campus Sorocaba – Sorocaba, São Paulo, Brazil 2 Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo – Piracicaba, São Paulo, Brazil 3 Royal Botanic Gardens Kew – Richmond, United Kingdom

Tropical forest habitats are characterized by the prevalence of plants bearing fleshy fruits dispersed by animals. In South America, the genus Eugenia stands out, with a high number of species and serving as a significant year-round producer of fleshy fruits. The evolution of fleshy fruits is considered a potential key innovation in the hyper-diversification of subtribe Myrteae and the large genus Eugenia. Our investigation focused on the hypothesis that variation in fleshy fruit traits within Eugenia is closely linked to infrageneric lineages. We aimed to determine if specific species groups display distinct patterns of fruit traits and whether these traits have evolved to enhance reproductive success by either attracting specific dispersers or reducing seed predation. Results revealed substantial variability in Eugenia fruit traits, with discernible trends within infrageneric groups. The predominant exocarp colour in sampled Eugenia fruits were dark purple and red, contrasting with a higher probability of ancestral colours being yellow. Ripened exocarp colour is relatively strongly associated with taxonomic sections, suggesting potential common ancestry. Larger-fruited species are rarer and concentrated in early diverging clades within Eugenia, offering a potentially informative taxonomic feature for these groups. The number of seeds, a labile trait within Eugenia, was commonly recorded as one, but early diverging clade species tend to produce fruits containing more than one seed. Pulp ratio exhibited a stronger association with taxonomic sections, suggesting that species from more recently diverging clades invest less energy in pulp production and instead allocate more resource to seed size. Our findings suggest that variation in fleshy fruit traits in Eugenia can help define infrageneric lineages. Specific groups of Eugenia species display unique patterns of fruit traits, and our evidence suggests that these traits may have evolved to maximize reproductive success by either attracting specific dispersers or minimizing seed predation.